Electromagnetic clock



Nov. 29, 1927.

L. HATOT ELECTROMAGNETIC CLOCK a Sheds-Sheet 1 Filed March 11. 192

' 1,651,119 L. HATOT ELECTROMAGNETIC CLOCK Fi ed March 11. 1925 3 Shasta-Sheet 2 Filed Karen 11. 1925 s sums-sheet a Patented Nov. 29, 1927.

UNITED STATES LEON HATQT, OF PARIS,-FRANCE.

ELECTROMAGNETIC CLOCK.

Application filed March 11, 1925, Serial N'o. 14,802, and in France March 21, 1924.

The present invention refers to clocks the pendulums of which have their oscillations maintained by periodical electromagnetic impulses of the known type wherein a part lifted at each oscillation by the ratchet wheel controlling the hands acts as a switch by coming into contact with a. contact spring.

The devices which are the object of presentinvcntion, are combined in order to reduce the amount of mechanical power necessary for controlling the hands and the switch and to allow a very precise and easy regulation of the several elements which have tobe considered in the work ing (chiefly of the point in the path of the pendulum where driving catch is to begin actuating ratchet wheel). Thereby, as explained hereinbelow, isochronism of oscillations can be obtained.

The invention has also for an object improvements in the shapes to be given to certain parts of the clock in order to reduce the cost price and to allow an easy moving of the clock.

The invention has for. a further object novel shapes and proportions for parts of a clock set up according to invention and provided with a comparatively short and light pendulum. Such a clock is shown, by way of example, on appended drawings at a scale, value of which will be given hereinafter.

On appended drawings: 7

Figs. 1", 1 and 1 show controlling parts of switch and switch itself as they used to be made, whereb some of the improvements which are set orth hereinbelow may be described in a more precise manner. Said parts and switch are drawn on a scale of 1/1 according to centimeter scale shown in E on Fig. 1.

Fig. 2 shows at the same scale the whole clock mechanism in front View, wherefrom the dial and its supporting plate are supposed to have been taken away.

Fig. 3 is a vertical section passing through shafts bearing hands.

Fig. 1. is a view of supporting plate behind dial together with the several parts which are mounted on said plate.

F igs. 5 5", 5 and 55. show on an enlarged scale an improved form of execution of the contact springs.

Figs. 6, 6 and 6 show on an enlarged scale another form of execution of the contact springs.

Fig. 7 is a partially sectional detail View at a scale of 5/1 of the ratchet wheel, catch and switch. 4 v Fig. 8 is a section along line w-y of parts shown on preceding figure.

On appended drawings Fig.1 shows on the scale 1/1 the known part-s which usually go to build up an electromagnetic clock of the type which is considered.

The spring 1 bears a part 2 which after each stroke oflthe pendulum comes between two teeth of the ratchet wheel 4 from where it is lifted each time the driving catch 3 makes a tooth of, the ratchet wheel advance.

Part 2 is mounted on the end of spring 1 and has the shape shown on an enlarged scale on Fig. 1*.

In order to ensure a correct working, part 2 must always be brought back, after each advance of the ratchet wheel, to the position in which it is shown on Fig. 1". To arrive at this result with certainty, practice shows it is necessary to bind spring 1 strongly enough to oblige part 2 to bear against ratch et wheel with a comparatively high pressure exerted in the direction of arrow f,. The reason of this is the inertia of wheel causes it to advance more than by the interval between two teeth: The edge R of part 2 bears on the inclined rear part MN of ratchet tooth and has a tendency to bring the wheel back; this backward movement is accompanied by a comparatively important slipping movement: In order to make sure this will happen in spite of the unevennesses on back part MN of the tooth, it is necessary to provide for a comparatively important force acting in the direction f,. The work of this force, when ratchet advances, is a loss of mechanical power and so is the work of the frictional forces between the slipping surfaces. Practice shows further that to provide for a good working and to prevent the making and regulation of the parts from being too difficult, the pitch of the ratchet toothwork should be comparatively great (above 2 millimeters). This makes the frictional losses still greater, as the tip N of the tooth moves at each oscillation, a distance equal to width of a tooth, whilst slipping on part 2.

Fi 1 shows a form of execution of switc Spring 1 bears a. pin 6 made out of a precious metal and adapted to come into contact with two parts 7 and8 also of precious metal. These parts are U-shaped and are riveted on two correspondin contact spring strips 9. In practice onfy one arm of each part 7 and 8 bears on pin 6. This construction obliges a comparatively great quantity of precious metal to be used whilst only a very small part thereof is really used for the electric contact itself.

Above described devices have been recalled to mind in order to show exactly what improvernents have been brought thereto, said improvements being described hereinbelow.

Figs. 2, 3 and 4 show how the several parts of a clock mechanism are put together according to presentinvention.

The pendulum bears at its lower part a magnet 10 controlled by a stationary electromagnet 11. All parts of mechanism are mounted on plate 12 placed behind the dial 13 of clock.

The gear system controlling the hands is shown at A. The spindle 14 of ratchetwheel and the spindles of the gear wheels pivot on pivots spindle 16 of regulating catch of ratchet. Said catch bears an arm 17 provided with a pin 18 coming into contact, at each actuating stroke of pendulumwith contact springs 19 and '20.

These contact springs and their support are shown in perspective on an enlarged scale on Fig. 5. Springs 19 and 20 are cut out of a thin stri of steel so as to appear as shown on ig. 5 They are superposed as shown on said figure so as to provide two very narrow strips brought close one to another and adapted to come into contact with contact pin 18. I

The ends of the springs are twisted and brought in a plane per endicular to that of springs themselves as 0 early shown on perspective view 5. Onthe other hand small cappings 21 of precious metal are placed on said ends of springs. Each cappin consists in a small and very thin plate olded up as shown on perspective views (Figs. 5 and 5). Mounting of springs is shown on Fig. 5. Springs 19 and 20 are secured on square-shaped support S by means of screws V. These provide also for holding plates P and P Through plate P, passes regulating screw 22 bearing on plate 23. Latter plate is less flexible than springs '19 and 20 which are brought to bear against end of same. Regulating screw 22 allows control of position of plate 23 on which, as stated, ends of springs bear.

Instead of two contact strips, four can be used. In view of this, spring 24 is superposed to springs 19 and 2021s shown in perspective on enlargedscale on Fig. 6. This spring 24 is cut out so as to form two strips. The ends of these are twisted and curved as shown on Fig. 6. and small cappings similar to capping .21 are secured on plates 15 and 15 on which also.

, spiral spring same. Springs 1920 and 24 are superposed as shown on Fig. 6*. The small cappings are placed very close one to another and are perpendicular to pin 18; thereby weight of precious metal necessary for making this in 18 borne by contact arm 17 can be consic erably reduced. For instance, it can be suflicient to use a small portion of a tube 25 of precious metal which is set round part of pin 18 coming into contact with SPIlIlgS.

Such forms of execution show over that drawn on Fig. 1", the obvious advantage to require a considerably smaller quantity of precious metal, the device working nevertheless under conditions absolutel as good.

Figs. 7 and 8 show on a sca e 5 times larger than centimeter scale in E, the ratchet,

catch and switch device.

The driving catch is suspended by means of a flexible strip 26 to of which is clam ed in stationary holder 2 borne by pendu um whilst lower end is clamped between parts 28 and 29. On part 30 secured to latter parts driving catch 31 is pivotally mounted. The regulating screw 32 allows the pivoting spindle 33 of the driving catch to move in direction of arrow f away from the pendulum. The screw 34 allows a regulation of depth of engagement of driving catch with the teeth of the ratchet-wheel 35 by raising more or less the end of the catch in the direc tion of arrow f The ratchet-Wheel 35 is cut as shown on Fig. 7 and shows semi-circular intervals between teeth. The regulating catch 36 is secured to spindle 16 and is provided with arm 17 bearing in its turn the contact pin 18. The electric current arrives through the 37 secured b one end to projection 38 of arm 36 and by the other to split collar 39 fitted with some friction on projection 40 cast with casing.

The end of regulating catch 36 shows two surfaces AB and BC iorming to ether a slightly obtuse angle (see Fig. 7 One of these surfaces AB is nearly parallel to the line w;z going from spindle 14 of ratchet wheel 35 to spindle 16 of the regulating catch. Said-surface bears on tip of tooth d, which is situated close to and directly above line 112-31. The regulating catch 36 has therefore a tendency,by reason of its weight and of the action of spiral spring 37, to force the ratchet wheel back through its action on the tooth l The ti of next tooth d comes then against and of surface BC so that device stops in a predetermined position. The following tooth d, is then placed in the path of the end of driving catch 31.

The momentum of inertia of regulating catch 36 and of its arm 17 is com aratively important. The total weight of t ese parts hould. e ab ve g mme, .On the other hand a rotation is imparted to the collar 39 which is suflicient to make the force which brings surface AB of the catch against the tooth al big enough to drive the ratchet wheel back until it is stopped by contact be tween tooth ti, and tip G of catch.

Lastly, by means of the screw 34, the depth of engagement ofthe driving catch 31 is regulated so as to force sazd catch to rotate tooth d, and to disengage it when the ratchet-wheel has advanced exactly the quantity corresponding to pitch of its toothwork.

The devices work in the following manner: v

When the drivin catch 31 comesi nto contact with the toot d the tooth d raises the regulating catch 36 and causes it to turn inthe direction of arrow f The speed of this rotation grows when speed of pendulum becomes greater. The pin 18 is thus caused to come into contact with the contact springs springs.

19 and-20 and the kinetic energy contained in the regulating catch serves to raise these advanced the value of one tooth interval, the regulating catch falls back and if ratchetwheel has advanced somewhat to much, the surface AB presses on tooth al whereby ratchet wheel is brought back in its correct position. Y

,It should be noted that the necessary 7 amount of energy for this object is much smaller than with device shown on Fig. 1*. The reason of this fact is the working force acts on a lever arm value of which is very near the radius of ratchet wheel and therefore near its maximum, value. Moreover there. is hardly any slipping whilst the return movement is being made, as the tooth d is nearly on the line joining the spindles' of ratchet-wheel and regulating catch. If surface AB is well polished and slightly lubricated, it will be a suflicient reason for avoiding jamming and allowing return movement to be made with a very small e'xpenditure of energy. Lastly the device is easy to make and the workingis most reliable, even with a very small pitch of the tooth work. Therefore a very small ratchet wheel can be used and the distance between supporting part 26 and driving catch 31 can be made very small. Thus all friction is This loss is approximately proportional to the square of the amplitude of the oscillations and it thus affords means for ensuring stability of operation and regularity of working. By means of regulating screw 32 it is possible to determine at will the moment; during stroke of pendulum when the drive As soon as the ratchet-wheel has greatly diminished and, as is well known,

sThe pendulum can of the drivingcatch is to begin and thereby the moment when the retarding percussion begins. The motive power is put into action during a time which can be regulated by and thereby the amplitude of the oscillations were to'vary, this would have no efiect on the period of oscillation and on the accuracy of the time-keeping.

The described devices allow this result to be easily achieved; all the elements which influence theoperation are very easily regulated with a very great precision. A greatly improved regularity can be thus obtained, the pendulum used being nevertheless comparatively very light and very short. Figs. 2, 3, 4, 3 and 3 show a preferred form of execution of the casing and other parts of clock mechanism.

All the parts are fixed on a foundation plate 12 over which is placed the dial 13 of the clock. The rod of pendulum is made out of a strip of invar metal 41 in one or more parts the top of which forms a socket borne by the suspending device.

The battery 42 is secured on a plate 43 attached to the foundation plate by means of projections 4 1. The terminals of the battery are connected, one with the contact spring 19 through the wire 59 and the other with the contact arm 17 through the wire 60, the stationary coil 11, and the spring 37.

The electromagnet 11 is secured to plate 43. The .dial and the hands 0 a (1 are protected by a glass 49 held between the two parts 50 and 51 which are made out of two brass sheets stamped and soldered one on the other. These parts form an openingrim for the .glass which is provided with hinge 52 mounted-on part 50 on one side and on foundation plate on the other by means of screws 53 and 54 (see section on enlarged scale on Fig. 3*).

The movable parts are fixed H1 clock casing by means of threaded rods such as 55 and stamped ring 57. A coverfitl which can be set on casing with some friction shuts rear opening of the clock after battery has been introduced in same.

The above described system of securingdevices allows an easy setting of an electrical control device in the casing of an ordinary spring clock without requir ng any change thereto. They are much easler, and cheaper to make than the usual hinged rims with bevelled glass.

be immobilized for transport by means of a screw passing through rod 41 of pendulum into a projection cast with casing. The rod of pendulum can also comprise a part 4=1 and a part 41 former of which holds the magnet, as shown on Figs. 3 and 3 This construction allows the removal of the heavier part of the pendulum for transport and the easy hooking on of same when clock is set up again.

The devices shown on Figs. 5 and 6 are conveniently used as an auxiliary switch actuated by the pendulum. It is sufiicient for this to secure uch a device in 0 as shown on Fig. 4 so as to cause a pin to raise the contact springs at each oscillation.

The working of the ratchet wheel and of the catch as described hereinabove can be used for the electric maintenance of any oscillating device and chiefly for that of an equilibrated pendulum cooperating with a spiral spring. In latter case, the above described devices are more particularlypseful, inasmuch as they reduce the friction which may arise, which is very important when the momentum of inertia of the pendulum is small.

What I claim is:

1. In a ratchet escapement comprising a driving catch secured to the clockpendulum, a ratchet wheel controlled by the driving catch, and a regulating catch engaging the ratchet wheel, a spindle on which the regulating catch is pivotally mounted, the regulating catch extending substantially parallel to the line connecting the spindle with the center of the ratchet wheel and ending with a plane surface making an obtuse angle with the said line whereby this surface eng es the interval between two teeth of the rate et wheel disposed near the abovementioned line, and means whereby the regulating catch brings back the ratchet wheel to the position corresponding to an advance equal to the interval between two teeth.

2. A ratchet escapement for electromagnetic clocks as claimed in claim 1 comprising a contact pin borne by the regulating catch, disposed in the electric circuit controlling the clock, a stationary contact spring cooperating therewith, two stationary plates between which the spindle of the regu- -'ting catch is mounted, a lateral arm borne by said regulating catch and bearing the contact pin, aspiral spring secured to said lateral arm, a socket secured to the spiral spring and a stationary pin on which said socket is filgictionally set and round which it is r0tata le.

3. A ratchet escapement for electromagnetic clocks as claimed in claim 1 comprising a slightly yielding part mounted on the pendulum and on which the driving catch is pivotally mounted, a regulating screw passing'through the yielding part and bearing against the pendulum, and a second regulating screw passing through the yielding part and bearing against the driving catch.

In testimony whereof I have signed my name to this specification.

LEON HATOT. 

